The long-term goal of the proposed work is a system that simulates the auditory-perceptual effects of hearing loss in combination with hearing aids, cochlear implants, or other auditory prostheses. This simulator will be completely wearable so that it can be used in everyday settings without occupying hands or eyes. Alternatively, it can be used while tethered to a computer for extensive changes of system characteristics. It will be a binaural system, with loss and prosthesis characteristics independently specifiable for the left and right channels, and it will provide simple controls so that when it is un-tethered from the PC the user can switch among several loss and prosthesis settings. The eventual goal is to make the simulator available at moderate cost (approximately $700) for the following applications: training audiologists and educators of the deaf; demonstrations in hearing- conservation and public education programs; demonstrations for families of hearing-impaired and deaf persons; demonstrations for prospective hearing aid users; and as a research tool. The work in Phase I will develop the core DSP technology for the system and will assess the feasibility of a hybrid method employing passive attenuation, masking noise, and automatic gain control that is expected to enable simulation of hearing losses as large as 100 dB for a user immersed in a sound field. PROPOSED COMMERCIAL APPLICATION: The primary market for the simulator consists of training programs in audiology and deaf-education, parent/relative-counseling programs, and researchers. The size of this market in the U.S. is estimated to be about a thousand units, with a similar-sized market in the rest of the world. A larger market group, though one with less motivation to purchase, is the roughly 10,000 hearing-aid dispensers in the U.S.